Source: typically the more energy your source outputs, the (much) better. Output impedance is part of the equation (W=V2/R, remember) -- but as usual line sources have a sort of standard 2V spec, the impedance is good indicator.
On the amp side, a relatively stable input of 10k ohm & above should be fairly OK across the acoustic spectrum.
Of course, you have the attenuator in between and its impedance changes will affect the result. The buffered option would keep the output impedance fairly stable across the board, which is probably why some people find it "better".
On the amp side, a relatively stable input of 10k ohm & above should be fairly OK across the acoustic spectrum.
Of course, you have the attenuator in between and its impedance changes will affect the result. The buffered option would keep the output impedance fairly stable across the board, which is probably why some people find it "better".